We have been investigating the use of an in vivo model system, to study potential agents for use in non-insulin requiring diabetes mellitus (NIDDM). Dr. B. Hansen, University of Maryland, has an extraordinary well characterized rhesus monkey model of this disease. We therefore gave two peptides, GIP and GLP, both known to have insulinotropic effects in other systems, to these monkeys. We ascertained the dose required to give half maximum insulinotropic effects. We showed that even the NIDDM monkeys can get an insulinotropic effect if given enough of these agents. We showed the glucose threshold required for insulin release by GLP. Further studies are planned using combinations of these peptides.